Gas injection apparatus

ABSTRACT

An activating gas chamber intimately mixes an activating gas with a nonwoven fabric as a pre-condition for interfilament bonding by increasing the velocity of the gas sufficiently such that complete penetration of the fabric by the gas is obtained in an enclosed environment.

States Patent alliance [451 Mar. 2, W72

[54] GAS INJECTION APPARATUS [72] Inventor: William C. Mallonee, 3741 Curtis Street,

Chester, Va. 23831 [22] Filed: Jan. 2,1970

[21] Appl. No.: 64

[52] U.S. Cl ..l56/381, 156/285 [5 l I int. Cl. ....B32b 31/26, B32b 17/04 [58] Field oiSearch ..l56/38l,497,499,285

[56] References Cited UNITED STATES PATENTS 3,295,167 l/l967 Corbin 1567497 ux 3,435,893 4/1969 Withers ..l56/285 X Primary Examiner-Benjamin A. Borchelt Assistant Examiner-4. J. Devitt Attorney-J. Bowen Ross, Jr., Russell E. Weinkauf, John D.

Upham and Neal E. Willis [5 ABSTRACT An activating gas chamber intimately mixes an activating gas with a nonwoven fabric as a precondition for interfilament bonding by increasing the velocity of the gas sufficiently such that complete penetration of the fabric by the gas is obtained in an enclosed environment.

1 Claims, 3 Drawing Figures BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a mixing chamber and, more specifically, to a chamber for receiving an activating gas from a source and for intimately associating the gas with each of the filaments comprising an unbonded nonwoven fabric so that, upon removal of the gas from the fabric, interfilament bonds are formed between adjacent and touching filaments.

2. Description of the Prior Art The use of a simple gas filled chamber to associate an activating gas with a nonwoven nylon web was described in U.S. lPat. application, Ser. No. 646,720, filed June 16, 1967, now Pat. No. 3,542,615, issued Nov. 24, I970. The use of an activating gas to bond nylon fibers was described in U.S. Pat. application, Ser. No. 737,507, filed June 17, 1968, now Pat. No. 3,5 16,900, issued June 23, 1970.

The above-identified applications comprise substantially all of the prior art relating to the association of an activating gas with a nonwoven unbonded fabric. In those applications, a simple container was supplied with the activating gas and the unbonded fabric was passed through the container with the dwell time being at least 1 minute to insure adequate association of the gas with the fabric. Since process speeds have significantly increased, dwell time of minutes and the like require that the gas activating container be extremely large. Therefore, other means for associating the activating gas with the unbonded web were investigated. Such investigation resulted in the invention as hereinafter set forth.

SUMMARY OF THE INVENTION A gas injection apparatus for applying continuously an activating gas to a moving nonwoven fabric is comprised of a receptacle container, a receptacle residing in the receptacle container, gas baffles mounted within the receptacle and perforated plates mounted in the receptacle between the gas baffles. The receptacle container is provided with opposed openings through which the continuously moving fabric passes and an exhaust means for removing the excess activating gas. The receptacle includes means for supplying the activating gas thereto and slots for allowing the moving fabric to enter and exit the same. The baffies are mounted within the receptacle adjacent the gas inlet pipes so that the gas may be properly dispersed throughout the receptacle. The pair of spaced apart perforated plates are mounted on and extend between the slotted opposed walls of the receptacle. The plates are in alignment with the slots to accommodate the passage of the fabric through the receptacle and to provide support for the fabric while in the receptacle. The perforated plates create a pressure differential between the area defined by the baffles and the receptacle walls and the area between the plates so that the activating gas will increase in velocity as it passes through the perforated plates. The increased velocity of the gas allows it to completely penetrate the nonwoven fabric from both sides.

Therefore, an object of this invention is to provide a gas injection apparatus which supplies an activating gas under pressure to a nonwoven fabric such that the gas completely penetrates the interstices of the fabric to prepare the touching and overlapping filaments for subsequent bonding.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a pictorial view of the gas injection apparatus showing the nonwoven fabric moving through the same;

FIG. 2 is a section view taken along lines 2-2 of FIG. 1 and showing the conduits for supplying the activating gas to the gas baffies; and

FIG. 3 is a section view taken along lines 3-3 of FIG. 1 and showing the path the fabric assumes as it moves through the apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In reference to the figures, the reference character 10 represents the entire apparatus which is comprised of a receptacle container 12, a receptacle 18 which is enclosed in receptacle container 12, and gas conduits I3 and 14 which supply the activating gas to receptacle l8.

Receptacle 18 is comprised of upper and lower walls 30 and 31, side walls 32 and 33 and end walls 36 and 37. Side walls 32 and 33 are respectively provided with slots 34 and 35 which accommodate the passage of the fabric 11 through receptacle 18. Receptacle 18 is also provided with a pair -of spaced apart, parallel and perforated plates 21 and 25 which are mounted on the side and end walls and which are aligned with slots 34 and 35. Perforated plates 21 and 25 are respectively provided with perforations or openings 22 and 26, respectively, which increase the velocity of the activating gas as the gas moves from receptacle 18 into the area defined by plates 21 and 25. Upper and lower baffies 19 and 23 are respectively mounted on upper and lower plates 30 and 31 and each provided with openings 24.

Conduits l3 and 14 respectively supply the activating gas under pressure to baffles 19 and 23, the gas being dispersed within receptacle 18 by means of openings 24 in baffies l9 and Receptacle 18 is mounted within receptacle container 12. Receptacle container 12 is a boxlike structure having openings 16 to provide passage-way for fabric 11 therethrough and exhaust 15 which may be connected to a vacuum source and which draws the activating gas exiting slots 34 and 35 away from the work area.

EXAMPLE I Continuous lengths of an unbonded nonwoven fabric comprised of continuous nylon 66 (polyhexamethylene adipamide) filaments were made in accordance with my copending application, Ser. No. 696,720,filed June 16, 1967.

The fabric, weighing 2.0 oz./yd. and having a thickness of 5.2 mils, was passed through the gas injection apparatus at a rate such that each portion of the fabric remained within the receptacle and in contact with the activating gas for 5 seconds. The activating gas was hydrogen chloride and was supplied to the receptacle through conduits 13 and 14 at a rate of 20 grams/minute.

Slots 34 and 35 had a width of 1 inch and perforated plates 21 and 25 were spaced apart in accordance with the slot width. Perforated plates 21 and 25 had a total surface area of 76 square inches. There were 55 holes in said two perforated plates with the diameter of each hole being l/32 inch. The velocity of the gas through the holes was 1,640 feet/minute.

Exhaust 15 was connected to a 1 inch vacuum source which removed the gas escaping receptacle 18.

The hydrogen chloride gas, which was absorbed by the nylon filaments, was subsequently removed by immersing the fabric in a water bath. The resulting bonded fabrics had a tenacity (pound/inch/ounce/yard square) of 4.5.

TABLE I I-lCl 20 Grams/Minute for 5 Seconds In Examples ll-VII, the slot width was inch, the fabric weight was 2.0 oz./yd. and the fabric thickness was 5.2 mils.

Each portion of the fabric remained in the gas injection apparatus for 5 seconds. Hydrogen chloride gas was fed to the receptacle at a rate of 20 grams/minute.

For adequate bonding, the slot width should be less than 1 inch so that the gas can penetrate the fabric and displace the outside air trapped therein. Also, the gas velocity should be below 3,200 feet/minute to allow adequate gas dispersion between the two perforated plates.

lclaim:

l. A gas injection apparatus for applying continuously a chemically activating gas to a continuously moving nonwoven fabric comprising an enclosed receptacle having upper, lower and a pair of opposed receptacle walls being interconnected and defining a chamber, said opposed walls each having elongated and aligned slots, first and second gas baffles mounted respectively on said upper and lower receptacle walls in said chamber, a chemically activating gas source, means for supplying said chemically activating gas from said source under a 7 positive pressure to said baffles, a pair of spaced apart perforated plates mounted on and extending between said opposed walls and being aligned with said slots to accommodate the passage of said fabric through said receptacle, said perforated plates creating a pressure differential between the area defined by the baffles and the receptacle walls and the area between said plates to increase the velocity of the activating gas through the perforated plates so that said gas completely penetrates said nonwoven fabric, a receptacle container enclosing said receptacle and forming a cavity therebetween, said receptacle container including elongated slots aligned with said receptacle slots to permit the passage of said fabric through said apparatus, a vacuum source and means connecting said vacuum source with said receptacle container to create a slight negative pressure in said cavity for venting the chemically activating gas exiting through said receptacle slots.

I! l 4 II 

